Magnetar Asteroseismology with Long-Term Gravitational Waves

TL;DR

This paper proposes a new approach to magnetar asteroseismology using long-term gravitational wave observations, which can reveal magnetic field evolution inside magnetars with next-generation detectors.

Contribution

It introduces the idea that long-duration GW signals from magnetars can be used to study their internal magnetic field evolution, extending beyond current short-term searches.

Findings

Long-term GW emission from magnetars can last days to months.

Frequency evolution of GWs can inform magnetic field decay.

Next-generation detectors can enable this asteroseismology.

Abstract

Magnetic flares and induced oscillations of magnetars (super-magnetized neutron stars) are promising sources of gravitational waves (GWs). We suggest that the GW emission, if any, would last longer than the observed X-ray quasi-periodic oscillations (X-QPOs), calling for the longer-term GW analyses from a day to months than the current searches. Like the pulsar timing, the oscillation frequency would also evolve with time because of the decay or reconfiguration of magnetic field, which is crucial for the GW detection. With the observed GW frequency and its time-derivatives, we can probe the interior magnetic field strength and its evolution to open a new GW asteroseismology with the next generation interferometers like advanced LIGO, advanced VIRGO, LCGT and ET.